Derivative Instruments and Hedging Activities - Fair Value of Derivative Instruments Reported in Condensed Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Apr. 03, 2015	Sep. 26, 2014
Derivatives Fair Value [Line Items]
Derivative assets	$ 1.0	$ 1.5
Derivative liabilities	0.2	0
Foreign exchange forward contracts | Derivatives Designated as Hedging Instruments | Prepaid expenses and other current assets
Derivatives Fair Value [Line Items]
Derivative assets	1.0	1.5
Foreign exchange forward contracts | Derivatives Designated as Hedging Instruments | Accrued Liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative liabilities	$ 0.2	$ 0